This invention relates to a novel and improved servo track configuration for magnetic disk apparatus.
In a magnetic disk apparatus employing a positioning servo system for positioning a read/write head relative to a desired data track of a magnetic disk, it is necessary to provide servo information which indicates the precise position of the read/write head. Suitable means for providing such servo information are employed in the servo track apparatus and the associated demodulator as disclosed in U.S. Pat. No. 3,534,344 to George R. Santana, "Method and Apparatus for Recording and Detecting Information" issued Oct. 13, 1970 , and in U.S. Pat. No. 3,691,543 to Francis E. Mueller, "Positioning System including Servo Track Configuration and Associated Demodulator" issued Sept. 12, 1972.
The servo information provided by the above-mentioned two systems in the form of periodic position signals, however, can hardly show whether the read/write head is approaching from a desired data track to an adjacent data track or is approaching to the desired data track after having left the desired data track. For this reason, the known magnetic disk apparatus employs a velocity detector for providing additional servo information which indicates both velocity and direction in which the read/write head is moving.